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Wyświetlanie 1-3 z 3
Tytuł:
Jubileusz metody miareczkowania kulometrycznego
An anniversary of coulometric titration
Autorzy:
Małyszko, J.
Powiązania:
https://bibliotekanauki.pl/articles/171793.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kulometria
miareczkowanie kulometryczne
miareczkowanie konwencjonalne
reakcje elektrodowe
titrants
coulometry
coulometric titration
conventional titrations
electrode processes
Opis:
In 1938, Szebellédy and Somogyi [1–7] have proposed an important methodological innovation in analytical chemistry. This methodology was termed coulometric titration. This paper presents an overview of the principles of operation and, in broad outline, applications of this methodology. Moreover, a short biography and scientific achievements of professor Laszlo Szebellédy are presented in the introduction. Chapter 1 of this review outlines the theoretical background and general description of coulometric titration. In this new technique, the electrical current generates a titrant that chemically reacts with an analyte. The amount of the analyte is determined from the quantity of the electrical charge passed until the point of chemical equivalence has been reached, according to the 2nd Faraday’s law of electrolysis. The new methodology offers several significant advantages over a conventional volumetric procedure, such as elimination of problems connected with the preparation, standardization and storage of standard solutions. In Chapter 2, an evolution of the method after the Second World War is presented. In these times, stable constant current sources became easy to construct [13–15]. Consequently, coulometric titrations started to use a constant current system. Under these conditions, the total number of coulombs consumed can be calculated readily from the intensity of current and the duration of electrolysis. Coulometric titrations have been developed for all types of volumetric titrations: oxidation–reduction [19–28], precipitation [17, 18], complex formation [37] and neutralization reactions [39, 40]. The generation of various titrants and possibilities of application are described. Special attention is devoted to the electrochemical generation of reagents which are not ordinarily utilized in conventional volumetric analysis owing to the instability of their solutions such as bromine, chlorine, silver(II) and titanium(III). Moreover, the coulometric titration procedure is significantly more sensitive than the volumetric titration, and it is particularly suited to automation, because complex mechanical devices such as an automatic burette are not required. The new method appeared to be an attractive alternative to all forms of the volumetric titration. Chapter 3 is dedicated to the contribution of Polish academic chemistry teachers to the development of the method discussed [57–89, 91–100]. Advantages and disadvantages of the method are listed in the last Chapter (Summary). Each Chapter includes selected works related to the history of the subject.
Źródło:
Wiadomości Chemiczne; 2011, 65, 5-6; 345-361
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Akumulatory litowo-jonowe stosowane w przemyśle motoryzacyjnym
The applications of lithium-ion batteries in automotive industry
Autorzy:
Knura, R.
Pacek, J.
Powiązania:
https://bibliotekanauki.pl/articles/171772.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
Li-ion
materiały elektrodowe
samochód hybrydowy
samochód elektryczny
electrode materials
hybrid electric vehicle
HEV
battery electric vehicle
BEV
Opis:
Due to limited resources of fossil fuels and overproduction of greenhouse gases, a need for alternative means for vehicle communication appeared. Because of that hybrid electric vehicles, as well as battery electric vehicles, were proposed to replace some of conventional vehicles based on internal combustion engine [3]. To their advantages over conventional cars belong environmental friendliness and better performance (in case of hybrid electric vehicles), but they also suffer from greater purchase costs and limited range (in case of most battery electric vehicles) [4, 6]. Presented work briefly characterizes four types of vehicles equipped with electric motor (mild hybrid, full hybrid, plug-in hybrid and battery electric vehicles) along with generalised presentation of their battery requirements [4, 6]. Further in this work, the lithium-ion (Li-ion) battery working principle was explained, along with characterisation of its limitations due to its design and requirements for inactive components e.g. 4-fold drop in specific capacity and energy density while moving from pure electrode material level to battery level [20]. Next, present Li-ion active components, such as LiCoO2, LiMnO2 and LiFePO4 cathodes and graphite anode along with their capacities and energy densities as well as other characteristic regarding (e.g. environmental friendliness, safety and cost) are shown. Moreover electrode materials e.g. nanocomposite anodes and cathodes, multi-electron cathodes (e.g. Li2MnSiO4), as well as Li-metal and Li4Ti5O12 anodes, with their advantages and disadvantages were described [15, 20]. Presented article was summarized by gathered opinions of battery electric vehicles users, who share their experience regarding their electric cars in a survey. One can tell that they are fairly satisfied with their purchase and that improvement in range of battery electric vehicles along with predictable government policy regarding electrification of cars are the most important factors when considering purchase of electric vehicle [36].
Źródło:
Wiadomości Chemiczne; 2018, 72, 3-4; 185-205
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elektrody jonoselektywne czułe na jony magnezowe w badaniu specjacji magnezu w organizmie ludzkim
Ion selective electrodes sensitive to magnesium ions in magnesium speciation research in human organism
Autorzy:
Maj-Żurawska, M.
Lewenstam, A.
Hulanicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/171985.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
jon magnezu
elektroda jonoselektywna czuła na jony magnezu
ISE
elektroda jonoselektywna
specjacja magnezu
analizator kliniczny
magnez w organizmie
magnesium selective electrode
magnesium speciation
clinical analyzer
magnesium in human
Opis:
Application of magnesium selective electrodes to magnesium ion determination in biomedical samples has been introduced to analytical chemistry since 1990- ies. Using ion selective electrode, the ionized magnesium concentration is determined. Until this time, mainly concentration of total magnesium was determined. In this work, the importance of magnesium and its role in the human organism is shortly presented. Then, we present basics of ion selective electrodes and their application in clinical analyzers. We show exemplary applications of ionized and total magnesium concentration determination in clinical samples, such as blood serum or plasma and erythrocytes, in healthy people and in patients with various diseases. In every case, the ionized magnesium concentration in erythrocytes appears to be the most sensitive indicator of hypomagnesemia that is the pathophysiologically lowered magnesium level in organism. The knowledge of this parameter allows physicians for better diagnosis of magnesium status in human organism.
Źródło:
Wiadomości Chemiczne; 2015, 69, 9-10; 671-685
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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